Exercise 1. Chapter 8.
Lab description:This program takes a string and returns it backwards.It was difficult to understand how to use this conditions for functions.

Code:

def letters_back(x):
    index=-1
    length=(-1*len(x))
    while index >= length:
        letter=x[index]
        print(letter)
        index = index-1
print(letters_back("fbs123456789"))

Screenshot:

Exercise 3. Chapter 10.

Lab description: The function cumulative _sum returns a new list that where the i-th element is the sum of first i+1 elements.It was not easy to figure out the return line.

Code:

def cumulative_sum(n):
    if len(n)<2:
        return n
    n[1]=n[0]+n[1]
    return [n[0]]+cumulative_sum(n[1:])
print (cumulative_sum([1,2,3,4,5,6,7,8,9]))

Screenshot: